CARACAS, Venezuela — A huge explosion rocked Venezuela’s biggest oil refinery early Saturday, killing at least 19 people and injuring more than 50 others in the deadliest disaster in memory in the country’s key oil industry.

Balls of fire rose over the Amuay refinery, one of the largest in the world, in video posted on the Internet by people who were nearby at the time.

Those killed included a 10-year-old boy, and at least 53 people were injured, Falcon state Gov. Stella Lugo said on state television. She said firefighters had controlled the flames at the refinery on the Paraguana Peninsula in western Venezuela.

“The areas that had to be evacuated were evacuated,” Lugo said, according to the state-run Venezuelan News Agency. “The situation is controlled. Of course they’re still a fire rising very high, but ... the specialists tell me there is no risk of another explosion.”

The blast occurred after 1 a.m. when a gas leak created a cloud that ignited, Oil Minister Rafael Ramirez said. Some nearby houses were damaged by the blast, he said on television.

Amuay is part of the Paraguana Refinery Complex, which also includes the adjacent Cardon refinery. Together, the two refineries process about 900,000 barrels of crude a day and 200,000 barrels of gasoline.